/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.values;



import com.bff.gaia.unified.sdk.Pipeline;

import com.bff.gaia.unified.sdk.transforms.PTransform;

import com.bff.gaia.unified.sdk.coders.Coder;



import java.util.Map;



/** The interface for things that might be output from a {@link PTransform}. */

public interface POutput {



  /** Returns the owning {@link Pipeline} of this {@link POutput}. */

  Pipeline getPipeline();



  /**

   * Expands this {@link POutput} into a list of its component output {@link PValue PValues}.

   *

   * <ul>

   *   <li>A {@link PValue} expands to itself.

   *   <li>A tuple or list of {@link PValue PValues} (such as {@link PCollectionTuple} or {@link

   *       PCollectionList}) expands to its component {@code PValue PValues}.

   * </ul>

   *

   * <p>Not intended to be invoked directly by user code.

   */

  Map<TupleTag<?>, PValue> expand();



  /**

   * As part of applying the producing {@link PTransform}, finalizes this output to make it ready

   * for being used as an input and for running.

   *

   * <p>This includes ensuring that all {@link PCollection PCollections} have {@link

   * Coder Coders} specified or defaulted.

   *

   * <p>Automatically invoked whenever this {@link POutput} is output, after {@link

   * PValue#finishSpecifyingOutput(String, PInput, PTransform)} has been called on each component

   * {@link PValue} returned by {@link #expand()}.

   */

  void finishSpecifyingOutput(String transformName, PInput input, PTransform<?, ?> transform);

}